megboyzzandClaude
9c4a455bb0
Every shim crossing took a std::mutex in MiscStubDispatch and five separate
uc_reg_read calls in import_stub_dispatch_cb. Measured at ~170,000 crossings
per second during gameplay, from several threads.
Dispatch table is now a fixed array plus an atomic published count. It is
append-only by construction (AllocCodeStub bump-allocates 4 bytes per stub
and refuses past the arena end), entries are never removed or rewritten, and
a writer fills its slot before publishing the count with release ordering -
so an acquiring reader always sees a complete entry. The mutex remains on
the append side, which runs a few hundred times at startup.
Register reads go through one uc_reg_read_batch instead of five API entries.
RESULT, and it is smaller than the reasoning predicted:
time to first OnCarLoaded 36.35s -> 35.20s (35.14 / 35.28 / 35.18)
About 3%, consistent across runs. The estimate that each crossing costs
~6us - derived by dividing a saturated core by the measured crossing rate -
implied far more headroom than this. Either the mutex and register reads
were a small part of the crossing cost, or the thread is not actually
saturated and the estimate is wrong. Recorded rather than explained away;
the change is correct and free either way, but it is not the lever the
arithmetic suggested.
Also adds temporary task #56 instrumentation, all opt-in:
- gles_shim PERF line: fps, draws/frame, shimCalls/frame in ONE line, so the
correlation is readable live instead of joined across logs afterwards.
- guest_engine TOPSHIMS line: the busiest shims once a second, counted per
ImportStubEntry so no shared map or mutex taxes the hot path.
Those two measurements corrected an earlier wrong conclusion. Draw calls
looked like the cause of the in-race slowdown the user demonstrated, but
with the crossing counter in place: draws/frame 178 vs 149 across a 4x fps
gap, while shimCalls/frame went 22,000 vs 5,600 - and fps falls out exactly
as crossings-per-second / crossings-per-frame (148350/4385 = 33.8,
167811/21665 = 7.7). Draws were a bystander.
Co-Authored-By: Claude <noreply@anthropic.com>